Combination tube closure and electrode for neon tubes



April 15, 1941. M. MILLER 2,238,277

COMBINATION TUBE CLOSURE AND ELECTRODE FOR NEON ITUBE5 Filed Feb. 9, 1940 Inventor MAURICE MIL 1 5,2 7

A tiorney Patented Apr. 15, 1941 COMBINATION TUBEOLOSURE AND ELECTRODE FOB NEON TUBES Maurice Miller, Latham, N. Y. Application February 9, 1940, Serial No. 318,154

10 Claim.

This invention relates to a closure and electrode for a neon or gaseous tube, the general object of the invention being to provide a metal closure for an end of a tube and to which an electrode is secured, with a sleeve of ceramic material enclosing the electrode.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts to be hereinafter fully described, illustrated in the accompanying drawing and specifically pointed out in the appended claims.

In describing the inventionin detail, reference will be had to the accompanying drawing wherein like characters denote like or corresponding parts throughout the several views, and in which:

Figure 1 is a view of a gaseous tube constructed inaccordance with this invention.

Figure 2 is a section on the line 2-2 of Figure 1.

Figure '3 is a section on the line l3 of Figure 2.

Figure 4 is a sectional view through a modified form of sleeve.

Figure 5 is a detail sectional view showing the cup as containing silica carbide.

In these views the numeral I indicates the glass tube of a neon, mercury or gaseous device and each end of the tube is closed by a metal cap 2 to which the tube end is fused. This cap should be of. such material as to have expansion qualities similar to the glass so that the cap will provide a vacuum tight joint for the end of the tube at all times. A small metal cup I has its closed and rounded end welded to the central portion of the inner face of the cap as's hown at l and a sleeve 5 of non-conductive material or of ceramic-like materialsurrounds the cup and is held in place by the cup by providing the sleeve with an internal annular lip 6 which extends under the cup as clearly shown in Figure 2.

The cap 2 securely seals the end of the tube so as to make a vacuum-tight joint. It also acts as means of electrical contact and discharge for the gas inserted in the tube. The cup 3 welded to the cap acts as a means of concentrating the arc and discharge to prevent are from traveling without control over the inside area of the metal can and the sleeve 5 acts as a means of controlling sputter discharge. It will be seen that this sleeve is secured in place when the cup is welded to the cap.

As will be seen the cap 2 has a concave major part, with its sides extending at substantially right angles. This form of cap facilitates its connection in a fluid-tight manner at the end of the tube.

By having the sleeve 5 held in'place by the cup 3 it is not connected with the cap so that there is no danger of breaking the sleeve when heat is applied for welding the cup to the cap.

As shown in Figure 4 a ring-shaped member 8 may be cemented or otherwise attached to the top of the sleeve, this ring-shaped member being of the same material as that of the sleeve and its use eliminates sputter.

Where strong electric currents are to be used in the device a body 9 of silica carbide or similar substance may be placed in the cup 3, as shown in Figure 5. This body, as illustrated, about half fills the cup and it is held in place in any suitable manner such as by the lips Ill in the cup.

The silica carbide may be coated with barium, thorium or other appropriate substances and its use will enable the electrode to withstand heavy or strong currents. w

In welding the cup to the cap I prefer to place a small piece of wire between the cup and the cap before starting the welding operation as I find this prevents too much heat being communicated to the tube which might crack the same and it places the cup a slight distance from the cap.

When it is desired to connect two of the tubes together this can be done by placing; one end of a tube closed by a cap 2 against the cap of another tube with a small coil spring between the parts to maintain contact with a sleeve of nonconducting material connecting the ends of the tubes together.

The cup 3 is preferably made of stainless steel or similar material treated to reduce voltage drop, the metal being preferably treated with barium, magnesium, thorium or the like.

It is thought from the foregoing description that the advantages and novel, features of the invention will be readily apparent.

It is to be understood that changes may be made in the construction and in the combination 7 and arrangement of the several parts provided whereby only a very short portion of said tube is covered thereby; a second metal cup secured at its bottom to the inside bottom of the first mentioned cup: and a sleeve of refractory material having a length in excess of the depth of said second cup laterally surrounding said second cup and having a portion extending under the bottom thereof and loosely engaged thereby.

2. A combined closure and electrode for the glass tube of a gaseous electric discharge device comprising a shallow metal cup adapted to fit closely over the end of said tube, whereby it may be readily fused thereto, and having a depth substantially less than its diameter, a second metal cup secured at its bottom to the inside bottom of the first mentioned cup, and a sleeve of refractory material having a length in excess of the depth of said second cup laterally surrounding said second cup and having its exterior spaced from the interior sides of said first mentioned cup to provide an annular space therebetween for the reception of the end of said tube.

3. A combined closure and electrode for the glass tube of a gaseous electric discharge device comprising a shallow metal cup adapted to fit closely over the end of said tube, whereby it may be readily fused thereto, agid having a depth substantially less than its diameter, a second metal cup secured at its bottom to the inside bottom of the first mentioned cup, and a sleeve of refractory material having a length in excess of the depth of said second cup laterally surrounding said second cup and having a portion extending between the bottoms of said cups securing said sleeve in place; the exterior of said sleeve being spaced from the interior sides of said first mentioned cup to provide an annular space therebetween for the reception of the end of said tube.

4. A combined closure and electrode for the glass tube of a gaseous electric discharge device comprising a shallow metal cup adapted to fit closely over the end of said tube, whereby it may be readily fused thereto, and having a depth substantially less than its diameter, a second metal cup having an exteriorly rounded bottom welded to the inside bottom of said first mentioned cup, and a sleeve of refractory material laterally surrounding said second cup and having an inwardly extending annular lip projecting under said second cup.

5. The structure set forth in claim 1 in which 0 tially closed by a separate disk of refractory material having a central aperture therein.

8. The structure set forth in claim 4 in which the end of the sleeve above the second cup is partially closed by a separate disk of refractory material having a central aperture therein.-

9. A combined closure and electrode for the glass tube of a gaseous electric discharge device comprising a cup formed of a metal alloy having a coeflicient of expansion approximating that of the glass in said tube and of an inside diameter adapting it to fit closely over the end of said tube, whereby it may be readily fused thereto to form a gas-tight seal, a second metal cup within said first mentioned cup and having its bottom secured to the bottom of said first mentioned cup, and a sleeve of refractory materia1 laterally surrounding said second cup and extending beyond the rim thereof; the exterior of said sleeve being spaced from the interior sides of said first mentioned cup to provide an annular space therebetween for the reception of the end of said tube.

10. A combined closure and electrode for the glass tube of a gaseous electric discharge device comprising a cup formed of a metal alloy having a coeflicient of expansion approximating that of the glass in said tube and of an inside diameter adapting it to fit closely over the end of said tube, whereby it may be readily fused thereto to [form a gas-tight seal, a second metal cup within 

